function initialize() {
      if (GBrowserIsCompatible()) {
        // define the crosshair tile layer and its required functions
        var crossLayer = new GTileLayer(new GCopyrightCollection(""), 0, 15);
        crossLayer.getTileUrl =  function(tile, zoom) {
          return "./include/tile_crosshairs.png";
        }
        crossLayer.isPng = function() {return true;}

        // Create a new map type incorporating the tile layer
        var layerTerCross = [ G_PHYSICAL_MAP.getTileLayers()[0],
                              crossLayer ];
        var mtTerCross = new GMapType(layerTerCross,
                                      G_PHYSICAL_MAP.getProjection(), "Ter+");

        var map = new GMap2(document.getElementById("map_canvas"),
            { size: new GSize(280,321) } );
        map.addMapType(G_PHYSICAL_MAP);
        map.addMapType(mtTerCross);
        map.setCenter(new GLatLng(56.050855, -2.798424 ), 12);
        map.addControl(new GLargeMapControl())

        var mapControl = new GHierarchicalMapTypeControl();
        
        // Set up map type menu relationships
        mapControl.clearRelationships();
        mapControl.addRelationship(G_SATELLITE_MAP, G_HYBRID_MAP, "Labels", false);
        mapControl.addRelationship(G_PHYSICAL_MAP, mtTerCross, "Crosshairs");
  
        // Add control after you've specified the relationships
        map.addControl(mapControl);
        Event.observe(window, 'unload', GUnload, false);
      }
    }

Event.observe(window, 'load', initialize, false);